1. Field of the Invention
The present invention pertains to artificial lenses for the eye and, more particularly, to intraocular lenses for surgical implantation in the eye.
2. Discussion of the Prior Art
The implantation of an artificial intraocular lens in an eye after removal of the natural lens due to a blindness-causing condition, such as cataract, has become an accepted practice. Such intraocular lenses are normally positioned in the posterior chamber of the eye, secured to the iris, or positioned in the anterior chamber of the eye. Anterior chamber intraocular lenses are desirable due to their advantages of requiring reduced manipulation for proper placement and of being suitable for use with intracapsular and extracapsular natural lens removal; however, in the past, anterior chamber intraocular lenses have suffered the disadvantages of requiring a precise measurement of the diameter of the anterior chamber or cornea to select the appropriate size implant and of the implanted intraocular lens irritating the cornea by riding thereagainst due to the insufficient flexibility of existing anterior chamber intraocular lenses. If the intraocular lens implanted is too small, movement of the intraocular lens in the anterior chamber can cause corneal irritation; and, if the intraocular lens implanted is too large, the Ugh syndrome, hyphema, and eye tenderness can occur. Accordingly, prior art anterior chamber intraocular lenses have had to be available in all sizes to the surgeon, and the surgeon must accurately determine the diameter of the anterior chamber before insertion of the intraocular lens or subject the patient to the trauma of implanting and removing intraocular lenses on a trial and error basis to find the proper size intraocular lens.
Accordingly, recently, it has become common to utilize posterior chamber intraocular lenses; however, the use of such lenses inherently requires precise and difficult manipulation of the intraocular lens for placement behind the iris; and, additionally, problems arise when the lens capsule is punctured or removed during removal of the natural lens. Thus, implantation of posterior chamber lenses effectively has been limited due to the surgical skill required in removal of the natural lens without puncturing the lens capsule and the surgical skill required to properly manipulate the implant lens for proper positioning in the posterior chamber. Even then, decentered lenses are not rare.
The practice of implanting intraocular lenses after natural lens removal due to cataract or other blindness-causing conditions is ever increasing; and, as more surgeons utilize this practice, rather than utilizing spectacles or contact lenses to provide focusing power after removal of the natural lens, the need for an intraocular lens that can be simply implanted with a minimum of trauma and minimum discomfort to the patient during surgery and thereafter has increased greatly. Thus, there has recently been a return to the use of anterior chamber intraocular lenses, and much effort has been expended to design anterior chamber intraocular lenses of a nature to be easily implanted in the anterior chamber via a single incision. However, such prior art anterior chamber intraocular lenses have had the disadvantages of often not being sufficiently flexible to be comfortably worn by a patient without irritation, not permitting simple implantation, or have created problems with pupillary capture.
In application Ser. No. 230,279, intraocular lenses for positioning in the anterior chamber of the eye are disclosed overcoming the above mentioned disadvantages of the prior art; and, it has been found that the three-point fixation provided by the embodiment of FIG. 10 is most advantageous for positioning in the anterior chamber. Three-point fixation has been proposed for anterior chamber intraocular lenses; however, prior to the invention of application Ser. No. 230,279, such three-point fixation anterior chamber intraocular lenses have utilized relatively rigid positioning members with the concomitant disadvantages mentioned above.
Intraocular lenses for positioning in the posterior chamber having three flexible filaments have been proposed as described in the article by C. William Simcoe in the American Intra-Ocular Implant Society Journal, Volume V, page 357, October, 1979. Intraocular lenses with flexible filaments having shapes similar to that shown in the Simcoe article or J-like shapes extending from lens bodies at various angles have at least one of the disadvantages of blocking the "angle" between the cornea and the iris by positioning too long a length of the filament in the angle when the intraocular lens is in place in the anterior chamber, easy unintentional insertion of the filament through the pupil into the posterior chamber as the intraocular lens is inserted in the anterior chamber and easy unintentional tucking of the filament in the folds of the iris as the intraocular lens is being inserted in the anterior chamber, the latter two disadvantages being greater when it is considered that the pupil and iris are often obscured by blood and aqueous humor during insertion of the intraocular lens.
There has been much effort expended to produce an anterior chamber intraocular lens of universal application due to the surgical complexities of implanting posterior chamber and iris-supported intraocular lenses; however, until the advent of the present invention as described hereinafter and in application Ser. No. 230,279, anterior chamber intraocular lenses have not been satisfactory due to the above described disadvantages thereof.